Increase in cytoplasmic calcium content in internodal cells of Lamprothamnium upon hypotonic treatment |
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Authors: | Y. OKAZAKI M. TAZAWA |
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Affiliation: | Department of Biology, Faculty of Science, University of Tokyo, Hongo, Tokyo, Japan |
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Abstract: | Abstract Internodal cells of Lamprothamnium succinctum, a brackish water Characeae, regulate turgor pressure in response to changes in external osmotic pressure (turgor regulation). When internodal cells were transferred to a hypotonic medium containing 3.9 mol m?3 Ca2+, the cell osmotic pressure decreased and the original turgor pressure was recovered. During turgor regulation Ca content of the cytoplasm increased significantly. Lowering the external Ca2+ concentration from 3.9 to 0.01 mol m?3 inhibited this increase in cytoplasmic calcium content. In a hypotonic medium containing 0.01 mol m?3 Ca2+, turgor regulation was inhibited as previously reported (Okazaki & Tazawa, 1986a). Thus transient increase in cytoplasmic Ca, probably in the ionized form, induced by hypotonic treatment may play an important role in turgor regulation. |
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Keywords: | Lamprothamnium Characeae Ca2+ turgor regulation |
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